Blade-securing means and method of making same



R. K. MQRCQM BLADE SECURING MEANS METHOD OF MAKING SAME .-Fil,ed Aug. 23,, 1921 mvsmoa. Regimw KQMommam H1 55 AT @NEY.

Patented Aug. 28, 1923.

UNHTED STATES vimra'rrr orrics.

REGINALD K. MORCOM, OF BIRMINGHAM, ENGLAND, ASSIGNOR TO GENERAL ELECTRIC COMPANY, OF SCHENECTADY, NEW YORK, A CORPORATION OF NEW YORK.

BLADE-SECURING MEANS AND METHOD OF MAKING SAME.

Application filed August 23, 1921. Serial No. 494,567.

(GRANTED UNDER THE PROVISIONS OF THE ACT OF MARCH 3, 1921, 41 STAT. L, 1313.)

T all whom it may concern Be it known that I, REGINALD KEBLE MoRooM, a subject of the King of Great Britain and Ireland, residing at Birmingham, in the county of Warwick, England,

have invented new and useful Improvements in Blade-Securing Means and Methods of Making Same (for which I have filed a patent application in Great Britain, 17th June, 1914, Patent No. 14598 of 1914), of

which the following is a specification.

The present invention relates to methods for attaching the blades, vanes or buckets of elastic fluid turbines or of other bladed contrivances for operating on fluids, such as fans or compressors, and the like to the supporting portions of the machine and particularly to the supporting wheel or rotor through which the working forces of the 9%) machine are required to be transmitted. The usual practice is to secure such blade elements in position by means of dove-tail joints or by riveting or upsetting. The blades however,

der dimensions as to render these methods somewhat precarious. The usual dove-tail method is generally found satisfactory where the stresses due to centrifugal forces are moderate and where the transfer of heat 39 between the blades and their supports is not of mate-rial importance. It has been found that where the centrifugal stresses or the temperature of the working fluid or both are high, that such constructions are not satisfactory.

I have invented or diseovered an improved construction for securing the blades in position which is free from the above 0-bjections and which is an improvement over 40 any prior arrangement with which I am familiar together with an improved method of making such a construction.

Some embodiments of my. invention are illustrated in the accompanying drawings in which Figure 1 is a sectional view of a construction showing one method of securing the blades in position;

Fig. 1* is a sectional plan view of one set of blades and; 1

Figure 1 is an elevation of the other set of blades taken at right angles to Figure 1.

Figure 2 is a plan and;

are usually of such. slen- Figure 2 a sectional elevation of a moditied construction;

Figures 3 and 3 are similar views of a further modification and;

Figures 4 and 4 similar views of yet a further. modification.

Figure 5 is a sectional elevation of an embodiment of the invention applied to a diiferent type of turbine Figure 6 is a radial sectional elevation an Figure 6 a side elevation partly in section of a modified form of construction.

F1gure 7 is an elevation of a construction similar toFigure 6 in which the radial width of the inner ring is so great that it virtually constitutes a disc and; 4

Figure 7 is a similar view of a slightly modified arrangement.

Referring particularly to Figures 1 and 1 and 1 the blades w are composed of lengths cut from a rolled strip of stock of suitable-section, the blades 0; being open ended at their free extremities. Short lengths b cut from another rolled strip of suitable section, are interposed between the blades at their root ends to serve as distance pieces or space blocks and are assembled within a short length 0 of channel section which serves as a carrier. The sides of the channel section 0 have a slight elastic set inwards towards one another sufficient to grip and retain the contained elements in place preparatory to the welding operation. Thus the said small elements are assembled together in the carrier 0 in correct relation to each other. Each group is subsequently united into a unitary mass by welding together the elements assembled in the carrier by providing copper or copper alloy incontact or proximity with the surfaces to be united which are made to fit accurately together and heating the whole together to the melting point of the copper or copper alloy in an atmosphere of hydrogen; the elements to be thus united being formed of steel which has a higher melting point than the copper or copper alloy employed as the uniting agent. i

In this welding'process, the copper in the presence ofhydrogen will penetrate even microscopic crevices of the surfaces of the steel and interlock itself therewith. The

presence of rust or scale on the surfaceof the steel greatly promotes the inseparabllity of the metals thus united by virtue of the fact that the iron becomes reduced pure iron by the hydrogen, the copper taking the place of the oxygen and thereby forming an alloy with the material of the surface of the steel components.

B .such a process, a very perfect unction of the assembled elements into an integral group can be relied on without danger of the deterioration of the metal of the thin blades to which it would be liable in carrying out the ordinary process of brazing.

A roup of the elements in the carrier 0 may enclosed in a muflle from whlch the air is evacuated by the admission of hydrogen and heated to a temperature at wh1ch the copper or cop-per alloy w ll melt. Such elements may be furnished with reinforclng wires 0? (Figure 1) or a stringer 1e ,(Flgure 1") and with a rivet f through the end distance piece or space block b (Figure 1f) or these reinforcing members may be omitted.

Under such circumstances, after cooling, the blade group; including the carrier of channel section 0 will constitute an integral unitary mass adapted to be secured to the rotor or stator of the machine, as for example, by' inserting them within annular grooves formed in the stator A and rotor B, and caulked in place by strlps A and BC,

The conformation of the blade groups or the carriers is such as to facilitate their assembly and secure attachment to the primary portions of the machlne the usual methods of upsetting, riveting, caulking and the like, enabling a new blade group to be substituted, with facility, for a group, the blades of which have. been deformed or otherwise injured. 7 Y

In the embodiments illustrated in Figures 3, 3 and 47, 4:, the distance pieces or space blocks b between the blades a are omitted, apertures 0' being punched through the bed or base of the channel-shaped carrier 0 to receive and to uniformly space the blades a. In Figures 2 and 2", the full width of the blades is retained throughout their length, the blades being prevented from moving in the direction of their length by wires 9.

In Figures 3 and 3 longitudinal movement of the blades is prevented by means of shoulders w formed at the root ends of the blades. .To facilitate the punching of the apertures 0' in the carrier 6:, the root ends "of the blades may be made still narrower and side strips IL insertedbetwee-n the narrow ends of the blades a and the sides of the channel 0 as seen in Figure 4.

- In the embodiment illustrated in Figure 5,

' the stator blades 0 with distance pieces or space blocks b are assembled in a channel carrier 0 as described above. The reduced outer extremities of the blades are riveted to thereto.

Messrs a shroud k of channel section. Into the hollow portion of the channel shaped shroud lo, the segment of a ring m is fitted and secured by means of rivets m. Adjustable strips n for reducing leakage are also lightly caulked to the ring m. A blade group. thus assembled is welded into an integral unitary mass as described in connection with the previous embodiments, In this manner, the blades are integrally welded to segments of rings at each of their ends. The rotor blades are similarly welded with interposed distance pieces or space blocks 0 of the section shown in Figure 5 and theintegral blade groups can be secured to the rotor in the manner shown in Figure 5 which is set forth in British Patent No. 23400 of 1905.

In Figures 6 and 6*, a method of construction for the stator blades similar to that set forth in British Patents 20394 of 1905 and 21214 of 1913 is ado ted, the metal welding being substituted or the riveting and interlocking described in the said British Patents;

In Figure 7 the inner ring is so wide radially as practically to constitute a disc and the distance pieces p are welded to the blades a and the rotor either singly or in groups and are assembled in thegroove q formed In Figure 7 the constructionof the stator blades is shown slightly modified.

What l claim as new and desire tosecure by Letters Patent of the United States is:

1. The method of forming a turbinelpart which comprises taking a carrying member, assembling elastic fluid directing elements thereonin spaced relation to each other and with the surfaces to be united in engage ment, fastening them in assembled-positions in the rotor wheel and pinned in a temporary manner, and then permanently uniting the engaging surfaces of the carrying member and elements by fusion of metal,

2. The method of'forming a turbine part which comprises taking a carrying member, assembling elastic fluid directing elements thereon in spaced relation to each other,

fastening them in a temporary manner so as to maintain surfaces to be united in engage ment, and then permanently uniting the carrying member and elements by copper brazing in an atmosphere of hydrogen o'r other reducing agent. r

3. The method of forming a turbine part which comprises taking a carrying member having a groove therein, assembling elastic fluid directing elements thereon with their root ends in the'groove' and with the surfaces to be united in engagement, fastening them in a temporary manner, and thenpermanentlyuniting the engaging fusion of metal.

4'. The method of forming a turbine part surfaces fluid directin which comprises taking a carrying member having a groove therein, assembling elastic elements thereon with their root ends in t e groove, fastening them in a temporary manner so as to maintain the surfaces to be united in engagement and then permanently uniting them by copper brazing in an atmosphere of hydrogen or other reducing agent.

5. The method of forming a turbine part which comprises taking a carrying member having a groove therein, assembling elastic fluid directing elements thereon with their root ends in the groove, and with spacing pieces between the root ends, fastening the carrying member, elements and distance pieces together in a temporary manner, so as to maintain the surfaces to be united in engagement, and then permanently uniting them by fusion of metal.

6. The method of manufacturing a turbine rotor which comprises forming segmental blade groups by assembling blades and spacing devices and uniting them by fusion of metal, and then fastening said blade groups individually to a blade carrying element.

7. The method of manufacturing a turbine rotor which comprises forming segmental blade groups by assembling blades and spacing devices and uniting them by fusion of metal, and then fastening said blade groups individually to a blade carrying element by a tongue and groove connection.

8. The method of manufacturing a turbine rotor which comprises providing segmental blade groups formed by assembling blades and spacing devices to form a segmental group and then uniting-them by fusion of metal, and a blade carrying element, said blade carrying element and blade groups being formed for tongue and groove connections with each other, assembling the segmental blade groups on the element by means of the tongue and groove connections, and fastening the blade groups individually to the element by pins.

9. The method of manufacturing a turbine rotor which comprises providing a blade carrying element having a groove therein and a plurality of blade groups having tongues, said blade groups being formed by assembling straight blades in spaced-relation to each other with spacing pieces between their roots, and unitin them by fusion of metal, mounting the b ade groups on the element with their tongues in the grooves, and then fastening the blade groups individually to the element by pins.

10. The method of manufacturing a segmental blade group for a turbine rotor which comprises taking a plurality of blade lengths cut from strips of suitable section, assembling them in a temporary manner with spacing pieces between their roots, and joining them into a unitary structure by fusion of metal.

11. The method of forming a turbine part which comprises takino' amember having a groove therein, assembling blades thereon with their root ends in said groove and distance pieces in the groove between such ends. and then uniting said member, root, ends and distance pieces by fusion of metal.

12. The method of forming a turbine part which comprises taking a member having a groove therein, assembling bladcsthereon with their root ends in said groove and distance pieces in the groove between such ends. and then unitin said member, root ends and distance pieces by copper brazing in an atmosphere of hydrogen or other reducing agent.

13. The method of manufacturing a rotor havinga blade ring thereon which comprises forming a number of segmental groups by assemb ng a plurality of blades and spacing devices into a segmental group and uniting them into a unitary mass by fusion of metal, and then fastening said groups individually on the rotor to form a ring of blades thereon.

14. A unitary blade group adapted for fastening to a turbine rotor comprising a plurality of blade lengths assembled in spaced relation to each other, with distance pieces between their root ends, said blade lengths and distance pieces being united by fusion of metal.

15. A unitary blade group adapted for fastening to a turbine rotor'comprising a plurality of blade lengths assembled in spaced relation to each other, with distance pieces between their root ends, said blade lengths and distance pieces being united by copper welding in an atmosphere of hydrogen.

16. In combination, a turbine rotor, and a number of segmental blade groups individually fastened thereon to form a blade ring, each blade group comprising a plurality of blades and spacing devices united by fusion of metal to form a unitary mass.

17. In combination, a turbine rotor,-a blade system therefor, said blade system being divided into arc-shaped groups, each of which comprises a plurality of blades of uniform section throughout their length with space blocks between their roots, said blades and blocks being brazed together to form a unitary mass, and means for securing the groups to the rotor. 18. A unitary blade group adapted f0 fastening to a turbine rotor comprising a plurality of blade lengths assembled in spaced relation to each other, with distance pieces between their root ends, said blade. length and distance pieces being united by a metal having a lower melting point than the metal forming the blades and distance pieces.

19. A unitary blade group adapted for fastening to a turbine rotor comprising a plu rality of blade lengths assembled in spaced relation to each other with distance pieces be- 5 tween their root ends, said blade length and distance pieces being united by a cuprous metal.

20. In combination, a turbine rotor, a blade system therefor, said blade system being divided into arc-shaped groups, each of 10 which comprises a plurality of blades of uniform section throughout their length with space blocks between their roots, said blades and blocks being united by a'cuprousmetal to form a unitary structure, and means for 15 securing the groups individually to the rotor.

REGINALD K. MORGOM. 

